The remark comes after the former Downing Street press secretary faced criticism for advising the public not to rinse their dishes before they put them into a dishwasher to help tackle climate change.
Stratton said that joining the Green Party was another way in which Britons could help save the planet from rising carbon emissions.
She told The Independent: 'When people say to me, 'What can they do?', the can do many things.
'They can join Greenpeace, they can join the Green Party, they can join the Tory Party.'Insurance Loans Mortgage Attorney Credit Lawyer
Boris Johnson's climate change spokeswoman Allegra Stratton has suggested people should join the Green Party to save the planet
She added: 'So there's lots of ways they can get involved in politics but for those people who wouldn't, how do you start to change your life in manageable, achievable, feasible, small ways.'
Stratton, 41, who is the chief spokesperson for this year's climate change conference, hosted in Glasgow, was responding to criticism by the Green Party and Greenpeace of her advice for Britons to take 'micro-steps' in order to be environmentally friendly.
A friend of Stratton told The Times that her quote about joining the Green Party was misleading.
'Allegra believes no government has done more for the environment and to deal with climate change in the UK than this one,' the source said. 'And no PM has given the issue such prominence and profile [as Boris Johnson].
'She's proud to be working for the PM to make Cop26 a success, encouraging other countries to come to Glasgow with real movement on coal, cars and trees and to stand a chance to limit temperature increase to 1.5 degrees.'
Green Party co-leader Jonathan Bartley welcomed Stratton's comments and told The Independent: 'After decades of inaction from both the Conservatives and Labour, we would absolutely agree with the government that joining the Green Party is the best thing people can do to help tackle climate change.'
He added: 'As we witness the Conservatives waste time talking about loading dishwashers and fantasy projects such as Jet Zero, it is reassuring to see that they do understand it is only the Greens who can bring about the real change that is needed if we are to prevent climate catastrophe.'
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The remark comes after the former Downing Street press secretary faced criticism for advising the public not to rinse their dishes before they put them into a dishwasher to help tackle climate change
Stratton said many British households are already taking the 'micro-steps' in order to be environmentally friendly.
She admitted that the government is not pretending that the steps taken on their own will 'stop climate change', but says the suggestions are intended could still have a positive impact.
Writing in The Telegraph, Ms Stratton said: 'Did you know, according to COP26 principal partner Reckitt, who make Finish, you don't really need to rinse your dishes before they go into the dishwasher?
'Does your brand of plastic bottle shower gel come as a bar in cardboard packaging? I bet it does. It might be freezing half a loaf of bread when you get it home, to get out later in the week, rather than throwing half of it away when it goes mouldy.'
Her remarks come amid the government's 'One Step Greener' campaign, intended to improve awareness of tackling climate change across Britain.
She also spoke ahead of the 2021 United Nations Climate Change Conference (COP26), set to take place in Glasgow in November.
The UK is pushing for an agreement at the Glasgow climate conference to limit global warming to 1.5C.
But Alok Sharma - appointed by the Prime Minister to lead the negotiations - said the target would be 'extremely difficult' to achieve without all the countries in the G20 signing up to a pledge to phase out coal.
Addressing reporters earlier this week, the former business secretary said rain and flooding 'sweeping London' while ministers were engaged in talks had sharpened their focus.
He added: 'I think it is a sober reminder on our own